1. Field of the Invention
This invention relates to a pipe insulator to seal and electrically insulate coupled pipes and the method of making the same. More specifically, it relates to a pipe insulator which includes a urethane seal portion formed in situ to provide an initial leakproof seal and a protective outer layer formed of continuous strands of resin saturated fiberglass.
2. Description of the Art
Various forms of pipe couplings have been proposed to address the need for a pipe coupling which provides an adequate seal and which is effective in electrically insulating the joined pipes. Many prior devices rely upon axial compression of a separately formed seal member to create a mechanical seal. U.S. Pat. Nos. 4,398,754; 4,066,283; 3,705,735; 3,462,175; and 3,266,821, for example, teach some of such devices. Most of such devices utilize coupling members or sleeves which must be axially moved by a threaded engagement. The use of such threaded arrangements, however, create a potential leak path and are therefore, undesirable. Further, the provision of a mechanical seal created by compression is inherently inferior to a bonded seal formed in situ. For example, a proper mechanical seal would not be created if insufficient axial force is applied during installation, if defective or non-uniform sealing surfaces are provided or if dirt or other contaminants are present at the location of the seal.
Other prior devices have proposed the formation of a seal formed in situ by various molding operations. U.S. Pat. Nos. 4,229,028 and 1,856,415 are illustrative of such devices. The formation of a seal in situ is believed to provide significant advantages over devices which utilize a mechanical seal but a major disadvantage of these methods and products is that they require the provision of expensive molds and a time consuming molding operation.
Additionally, various prior art devices including, for example, U.S. Pat. Nos. 4,229,028; 4,147,381; and 3,553,164 provide either an inner or an outer layer of resin embedded fiberglass windings. However, these prior devices and methods fail to recognize the importance of the winding pattern in providing maximum strength against a variety of stresses to which the coupling is likely to be exposed.
Accordingly, there remains a need for an insulating pipe coupling which provides a seal portion formed in situ without the need for expensive molds or a time consuming molding process. There remains a further need for such a coupling which provides increased strength against a variety of stresses to which the coupling will be exposed. And still further, there remains a need for a simplified method of manufacture which reduces the time and cost of manufacturing an insulating coupling and which creates a superior product.